Dihydropyrazole Derivatives Act as Potent α-Amylase Inhibitors and Free Radical Scavengers: Synthesis, Bioactivity Evaluation, Structure-Activity Relationship, ADMET, and Molecular Docking Studies.

Dihydropyrazole (1-22) derivatives were synthesized from already synthesized chalcones. The structures of all of the synthesized compounds were confirmed by elemental analysis and various spectroscopic techniques. Furthermore, the synthesized compounds were screened against α amylase as well as investigated for antioxidant activities. The synthesized compounds demonstrate good to excellent antioxidant activities with IC50 values ranging between 30.03 and 913.58 µM. Among the 22 evaluated compounds, 11 compounds exhibit excellent activity relative to the standard ascorbic acid IC50 = 287.30 µM. Interestingly, all of the evaluated compounds show good to excellent α amylase activity with IC50 values lying in the range between 0.5509 and 810.73 µM as compared to the standard acarbose IC50 = 73.12 µM. Among the investigated compounds, five compounds demonstrate better activity compared to the standard. In order to investigate the binding interactions of the evaluated compounds with amylase protein, molecular docking studies were conducted, which show an excellent docking score as compared to the standard. Furthermore, the physiochemical properties, drug likeness, and ADMET were investigated, and it was found that none of the compounds violate Lipiniski's rule of five, which shows that this class of compounds has enough potential to be used as a drug candidate in the near future.

Antioxidant and Cytotoxic Activity of a New Ferruginan A from Olea ferruginea: In Vitro and In Silico Studies.

Studies of the ethyl acetate extract bark extract of Olea ferruginea led to the isolation of one new compound Ferruginan A (1) in addition to two known compounds, Ferruginan (2) and cycloolivil (3). Structures of the isolated compounds were confirmed by mass spectrometry (MS) and NMR spectral data. The ethyl acetate fraction and compounds (1-3) were evaluated against breast cancer cell line (MCF-7) and as antioxidants using the free radical scavenging assay. Results revealed that compound 2 exhibits significant antioxidant activity with an IC50 value of 21.74 µg/mL. In addition, the ethyl acetate fraction showed good cytotoxic activity (79.31% inhibition at 250 µg/mL), whereas compounds 1-3 exerted mild cytotoxic activity (IC50 = 8.03-12.01 µg/mL) as compared to the standard (IC50 = 4.41 µg/mL) against MCF-7. Docking studies suggested that antioxidant activity is due to the chelation of compounds with copper present in the active site of tyrosinase. These results suggest that the extract exhibits considerable antioxidant activity, and the isolated compounds exert moderate anticancer activity.

In vitro α-glycosidase and urease enzyme inhibition profile of some selected medicinal plants of Pakistan.

The current study aims at exploring enzyme inhibition of four species of medicinal herbs, namely Senna bicapsularis, Thevetia peruviana, Nerium oleander and Vinca major. Plant selection was done on the basis of their therapeutic uses by local practitioners. The crude methanolic extracts of these plants were tested for their α-glycosidase and urease enzyme inhibition potential. The observed urease inhibitory potential for the crude extract of S. bicapsularis, T. peruviana and N. oleander were 8.3 ± 0.33 µg, 6.98 ± 0.98 µg and 9.56 ± 1.43 µg, respectively while the V. major did not show any inhibition. In addition, the IC50 value for Thiourea was 22.3 ± 1.14 µg. The crude extracts of S. bicapsularis, T. peruviana, N. oleander, V. major were shown to inhibit α-glycosidase activity with an IC50 value of 630.3 ± 0.03 µg, 700.7 ± 2.43 µg, 430.4 ± 3.97 µg, and the standard (acarbose) 880 ± 1.03  µM, respectively. Based on the TLC profile, the extract of S. bicapsularis was subjected to column chromatography and the major component named rhein (1) was identified. Compound 1 exhibited excellent urease and α-glycosidase inhibitory activity with an IC50 value of 7.4 ± 0.32 and 622.3 ± 1.03 µM, respectively.

Chemical and Pharmacological Evaluation of Hulls of Prunus dulcis Nuts.

Researchers have shown that the almond hulls, normally wasted after utilization of nuts, contain a number of biologically active compounds based on which the present study has been carried out. Focus is placed on the mass spectrometric determination of the analytes along with the estimation of total polyphenolic and total flavonoid contents in the 70% ethanol extract. After partitioning the 70% ethanol extract in hexane, chloroform, ethyl acetate, n-butanol, and water, all the extracts were evaluated for their antioxidant, antidiabetic, and antimicrobial activities. The results delivered total polyphenolic compounds as gallic acid equivalents (1% w/w) of the dried extract and total flavonoid contents as quercetin equivalents (0.2% w/w) of the dried extract. Mass spectrometric analysis resulted in the identification of 15 compounds containing various derivatives of (epi)catechin, chlorogenic acid, kaempferol, isorhamnetin and their glycosides, ursolic acid, amygdalactone, and benzoic acid derivatives. Antioxidant activity experiments showed that highest activity was found in n-butanol extract among the studied samples with IC50 value as 76.04 µg/ml, while hexane and chloroform extracts were active against the PTP1B enzyme with IC50 values 9.66 µg/ml and 37.95 µg/ml, respectively. Hexane and chloroform fractions were active against Staphylococcus aureus with the zone of inhibition diameter 9 mm and 12 mm, respectively.

Determination of total polyphenolic compounds and flavonoids in Matricaria chamomella flowers.

Matricaria chamomella is of medicinal importance and has been used for its various pharmacological activities against different diseases due to the presence of polyphenolic compounds especially flavonoids and their glycosides. Flowers of the chamomile plant were studied for the quantification of total polyphenolic compounds and flavonoids aglycon. Total polyphenolic compounds obtained were 83.22mg as gallic acid equivalents/g of plant material; while for the determination of flavonoids aglycon the plant material was subjected to acid hydrolysis before quantification through HPLC-PDA. Results showed that luteolin, quercetin, apigenin, isorhamnetin and kaempferol were quantified. Apigenin was found in highest concentration (0.071mg/ml) while amounts of the rest of the flavonoids quantified are: luteolin (0.012mg/ml), quercetin (0.032mg/ml), kaempferol (0.001mg/ml) and isorhamnetin (0.023 mg/ml).

Total polyphenolic compounds, total flavonoids, GC-MS analysis of volatile constituents, evaluation of antioxidant and antimicrobial activities of Prunus dulcis nuts.

Prunus dulcis has been known as a source of nutrients in many traditional foods and as a source of important biologically active compounds in traditional medicines. The present study describes the determination of total polyphenolic compounds, total flavonoids and GC-MS analysis of hexane and chloroform fractions of 70% ethanol extract of whole almond shelled seed. Antioxidant and antimicrobial activities of various extracts of the nuts were evaluated. Folin-Ciocalteau procedure resulted in total polyphenolic compounds as 0.008 mg (gallic acid equivalents)/mg of the dried extract and amount of total flavonoids contents yielded were 0.001 mg (quercetin equivalents)/mg of the nuts dried extracts. GC-MS analysis of the hexane and chloroform fractions yielded a number of volatile constituents, resulting in highest amounts of 6-Octadecenoic acid and 1,1,3,3-Tetramethyl cyclopentane as 37.52% and 24.54% in hexane and chloroform fractions respectively. Antioxidant activity using the DPPH radical scavenging assay resulted in very low activity in all the extracts. Only n-butanol extract showed mild activity against the gram negative E. coli with inhibition zone diameter 8 mm while rest of samples did not show any activity against any microbial strains under study.

Isolation, characterization and DFT studies of epoxy ring containing new withanolides from Withania coagulans Dunal.

A new withanolide named as withacoagulin J (1) along with a known withanolide H (2) from Withania coagulans Dunal are reported in this paper. The isolated compounds were elucidated by using 1D-NMR (1H NMR, 13C NMR) and 2D-NMR including homonuclear (COSY, NOESY) and heteronuclear (HSQC, HMBC); along with Mass spectrometry, UV-Visible and IR spectroscopic techniques. The molecular formula based on Fast-Atom Bombardment Mass Spectrometry [FAB-MS (M + 1)] for 1 and 2 were deduced as C28H37O5 and C28H39O6 with m/z values 453.2624 and 471.6041, respectively. The quantum mechanical studies of both compounds are based on DFT calculations. The DFT studies show band gaps of 4.86 and 4.83 eV for 1 and 2, respectively. The band gaps of 1 and 2 reflect high stability and resistivity towards oxidation-reduction reactions. The energies of HOMO and LUMO for compound 1 are -6.11 and -1.25 eV and for compound 2: -6.47 and -1.64 eV respectively. Theoretical and experimental FTIR data closely match for both the compounds which support the high accuracy of the computational protocol selection. Other parameters such as bond lengths, bond angles and dihedral angles for both compounds are also studied.

Accelerating Photocatalytic Hydrogen Production and Pollutant Degradation by Functionalizing g-C3N4 With SnO2.

Energy crises and environmental pollution are two serious threats to modern society. To overcome these problems, graphitic carbon nitride (g-C3N4) nanosheets were fabricated and functionalized with SnO2 nanoparticles to produce H2 from water splitting and degrade 2-chlorophenol under visible light irradiation. The fabricated samples showed enhanced photocatalytic activities for both H2 evolution and pollutant degradation as compared to bare g-C3N4 and SnO2. These enhanced photoactivities are attributed to the fast charge separation as the excited electrons transfer from g-C3N4 to the conduction band of SnO2. This enhanced charge separation has been confirmed by the photoluminescence spectra, steady state surface photovoltage spectroscopic measurement, and formed hydroxyl radicals. It is believed that this work will provide a feasible route to synthesize photocatalysts for improved energy production and environmental purification.

Evaluation of the Antidiabetic Activity and Chemical Composition of Geranium collinum Root Extracts-Computational and Experimental Investigations.

The root of Geranium collinum Steph is known in Tajik traditional medicine for its hepatoprotective, antioxidant, and anti-inflammatory therapeutic effects. The present study was conducted to evaluate of potential antidiabetic, antioxidant activities, total polyphenolic and flavonoid content from the different extracts (aqueous, aqueous-ethanolic) and individual compounds isolated of the root parts of G. collinum. The 50% aqueous-ethanolic extract possesses potent antidiabetic activity, with IC50 values of 0.10 µg/mL and 0.09 µg/mL for the enzymes protein-tyrosine phosphatase (1B PTP-1B) and α-glucosidase, respectively. Phytochemical investigations of the 50% aqueous-ethanolic extract of G. collinum, led to the isolation of ten pure compounds identified as 3,3',4,4'-tetra-O-methylellagic acid (1), 3,3'-di-O-methylellagic acid (2), quercetin (3), caffeic acid (4), (+)-catechin (5), (-)-epicatechin (6), (-)-epigallocatechin (7), gallic acid (8), ß-sitosterol-3-O-ß-d-glucopyranoside (9), and corilagin (10). Their structures were determined based on 1D and 2D NMR and mass spectrometric analyses. Three isolated compounds exhibited strong inhibitory activity against PTP-1B, with IC50 values below 0.9 µg/mL, more effective than the positive control (1.46 µg/mL). Molecular docking analysis suggests polyphenolic compounds such as corilagin, catechin and caffeic acid inhibit PTP-1B and ß-sitosterol-3-O-ß-d-gluco-pyranoside inhibits α-glucosidase. The experimental results suggest that the biological activity of G. collinum is related to its polyphenol contents. The results are also in agreement with computational investigations. Furthermore, the potent antidiabetic activity of the 50% aqueous-ethanolic extract from G. collinum shows promise for its future application in medicine. To the best of our knowledge, we hereby report, for the first time, the antidiabetic activity of G. collinum.

Quantification of polyphenolic compounds and flavonoids in Achillea millefolium and Equisetum arvense.

Flavonoids have been of considerable importance and interest because of their medicinal activity. Responding to their numerous health benefits, a comparative study on the quantitative determination of total polyphenolic compounds and flavonoids was carried out in Achillea millefolium and Equisetum arvense. Total polyphenolic compounds were quantified by Folin-Ciocalteau method using different solvents in order to prove their extraction efficiency. Focus within total polyphenolic quantification study was placed on the traditional reflux and solvents used were: water, 100% acetone, 100% ethanol, 80% ethanol, 50% methanol and 70% methanol. In order to make flavonoids free from glycosidic moiety for quantification, hydrolysis was performed in 50% MeOH at 90°C using 6 M HCl concentration. Reverse phase high performance liquid chromatography (RP-HPLC) in gradient elution mode at 50°C using Hypersil BDS (RP-18) column was employed for the separation of flavonoids. Mobile phase used consisted of different combinations of water-methanol-tetrahydrofuran-phosphoric acid. Flavonoids quantified were luteolin, quercetin, apigenin, isorhamnetin and kaempferol.

Short Communication: Evaluation of the chemical composition of essential oil of Thuja occidentalis leaves grown in Peshawar, Pakistan by gas chromatography mass spectrometry.

Essential oil extracted from the fresh leaves of Thuja occidentalis were evaluated for its chemical composition employing GC-MS. Total of twenty nine components were identified and determined quantitatively using the area normalization procedure. Alpha-pinene and (+)-4-carene were found in high amount with a percentage concentration of 54.78 and 11.28 respectively. Other compounds which yielded appreciable amounts are: alpha-cedrol (6.87%), terpinolene (5.88%), p-menth-1-en-8-ol acetate (5.21%), beta-myrcene (4.04%), beta-pinene (2.26%), germacrene D (1.72%), sabinene (1.65%) and D-Limonene (1.62%).

Development of HPLC Protocol and Simultaneous Quantification of Four Free Flavonoids from Dracocephalum heterophyllum Benth.

Quantification of the four flavonoids, namely, luteolin, kaempferol, diosmetin, and chrysosplenetin, has been performed for the first time in 80% ethanolic extract of Dracocephalum heterophyllum B. through HPLC coupled to UV detector after optimization of extracting solvent and chromatographic conditions. Total flavonoids quantified were 0.324 mg/mL of the extract. HPLC analysis delivered contents of the luteolin, kaempferol, diosmetin, and chrysosplenetin as 0.08%, 0.14%, 0.28%, and 0.79% of the dried extract, respectively. LOD (%) values calculated were 0.04, 0.03, 0.03, and 0.08 and LOQ (%) values were 0.08, 0.12, 0.11, and 0.28 for luteolin, kaempferol, diosmetin, and chrysosplenetin, respectively. The recovery percentages for these flavonoids were within the acceptable range of 95% to 105%. Standard deviation and %RSD were calculated for each target analytes individually in extract for determining the reproducibility and accuracy of the method. In no case the %RSD was higher than 1 taking retention time as a factor while in the case of area under the curve maximum %RSD was noted in the case of diosmetin as 2.85. From our literature review regarding the plant species under study, it appears that these flavonoids have not been quantified before and are reported for the first time in this paper.

Phytochemical Profiling and Evaluation of Pharmacological Activities of Hypericum scabrum L.

Phytochemical investigations of ethyl acetate-soluble part of the aerial part of Hypericum scabrum L. delivered eight pure phenolic compounds 1-8. The pure compounds were identified through physico-chemical, NMR (1D, 2D) and mass spectrometric studies as: 3-8''-bisapigenin (1), quercetin (2), quercetin-3-O-α-l-arabinofuranoside (3), quercetin-3-O-α-l-rhamnoside (4), quercetin-3-O-ß-d-glucopyranoside (5), quercetin-3-O-ß-d-galactopyranoside (6), (-)-epicatechin (7), (+)-catechin (8). Total polyphenolic compounds and total flavonoids contents were determined in the extract as 0.107 mg∙mg-1 and 0.023 mg∙mg-1 of the dried extract, respectively. Antioxidant activity using DPPH free radical scavenging assay delivered very strong activity for compounds 2 and 5, 6 and crude extract 10. Protein tyrosine phosphatase 1B (PTP-1B) inhibition experiment of isolated compounds and crude extracts resulted in significant inhibition activity for samples 2, 7a, 8a, 11 and 12 with IC50 values ranging from 1.57 to 2.91 µM. Antimicrobial activity of the pure compounds and extracts produced average results against Staphylococcus aureus, Escherichia coli and Candida albicans strains. From our literature survey, it appears that all pure compounds except 2 were isolated and reported for the first time in H. scabrum.

Determination of total polyphenolic compounds and flavonoids in Juglans regia leaves.

Juglans regia leaves have been widely used in traditional medicines because of its antimicrobial, antihelmintic, astringent, keratolytic, antidiarrhoeal, hypoglycaemic, depurative, tonic, carminative activity. Total polyphenolic compounds were determined using the Folin-Ciocalteau method and flavonoids were quantified using the HPLC-PDA after the hydrolysis of the plant material with HCl. Among the flavonoids myricetin, quercetin, apigenin and kaempferol were found in appreciable amount.

Quality control of herbs: determination of amino acids in Althaea officinalis, Matricaria chamomilla and Taraxacum officinale.

Analysis of raw materials and final products need reliable methods for the standardization of natural product drugs. Legal guideline also emphasizes on the qualitative and quantitative analyses of the plant constituents in an herbal product. In this study, thin layer chromatography (TLC) and amino acid analyzer was used for the determination of amino acids in plant extracts. Samples for this study were standards and aqueous extracts from Althaea officinalis, Matricaria chamomilla and Taraxacum officinale. Different amino acids in the extracts were detected through TLC. An automatic amino acid analyzer was used for the quantification of amino acids in the plant extracts under study.

Determination of carbohydrates in medicinal plants--comparison between TLC, mf-MELDI-MS and GC-MS.

INTRODUCTION: Quality control in the pharmaceutical and phytopharmaceutical industries requires fast and reliable methods for the analysis of raw materials and final products. OBJECTIVE: This study evaluates different analytical approaches in order to recognise the most suitable technique for the analysis of carbohydrates in herbal drug preparations. METHODOLOGY: The specific focus of the study is on thin-layer chromatography (TLC), gas chromatography (GC), and a newly developed mass spectrometric method, i.e. matrix free material enhanced laser desorption/ionisation time of flight mass spectrometry (mf-MELDI-MS). Samples employed in the study were standards and microwave-assisted water extracts from Quercus. RESULTS: TLC analysis proved the presence of mono-, di- and trisaccharides within the biological sample and hinted at the existence of an unknown carbohydrate of higher oligomerisation degree. After evaluation of different derivatisation techniques, GC-MS confirmed data obtained via TLC for mono- to trisaccharides, delivering additionally quantified values under a considerable amount of time. A carbohydrate of higher oligomerisation degree could not be found. The application of mf-MELDI-MS further confirmed the presence of carbohydrates up to trisaccharides, also hinting at the presence of a form of tetrasaccharide. Besides this information, mf-MELDI-MS delivered further data about other substances present in the extract. Quantitative determination resulted in 1.750, 1.736 and 0.336 mg/mL for glucose, sucrose and raffinose respectively. CONCLUSION: Evaluation of all three techniques employed, clearly proved the heightened performance of mf-MELDI-MS for the qualitative analysis of complex mixtures, as targets do not need modification and analysis requires only a few minutes. In addition, GC-MS is suitable for quantitative analysis.

Matrix-free and material-enhanced laser desorption/ionization mass spectrometry for the analysis of low molecular weight compounds.

The application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) for the analysis of low molecular weight (LMW) compounds, such as pharmacologically active constituents or metabolites, is usually hampered by employing conventional MALDI matrices owing to interferences caused by matrix molecules below 700 Da. As a consequence, interpretation of mass spectra remains challenging, although matrix suppression can be achieved under certain conditions. Unlike the conventional MALDI methods which usually suffer from background signals, matrix-free techniques have become more and more popular for the analysis of LMW compounds. In this review we describe recently introduced materials for laser desorption/ionization (LDI) as alternatives to conventionally applied MALDI matrices. In particular, we want to highlight a new method for LDI which is referred to as matrix-free material-enhanced LDI (MELDI). In matrix-free MELDI it could be clearly shown, that besides chemical functionalities, the material's morphology plays a crucial role regarding energy-transfer capabilities. Therefore, it is of great interest to also investigate parameters such as particle size and porosity to study their impact on the LDI process. Especially nanomaterials such as diamond-like carbon, C(60) fullerenes and nanoparticulate silica beads were found to be excellent energy-absorbing materials in matrix-free MELDI.

Online coupling of thin layer chromatography with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: synthesis and application of a new material for the identification of carbohydrates by thin layer chromatography/matrix free material enhanced laser desorption/ionization mass spectrometry.

This article describes the online hyphenation of thin layer chromatography with matrix free material enhanced laser desorption/ionization mass spectrometry (mf-MELDI-MS), the preparation of new material for MELDI and application of this newly synthesized material using TLC/MELDI-MS for the analysis of carbohydrate reference standards and plant extracts. Samples included within these analyses are standard solutions of glucose, sucrose, raffinose and a plant extract of Quercus robur, which is used for its anti-inflammatory, anti-viral and anthelminitc properties in phytomedicine. A new material for mf-MELDI-MS is prepared by immobilizing bradykinin--a peptide, on silica gel coupled to 4-(3-triethoxysilylpropylureido)azobenzene. This modification enables the absorption of laser energy sufficient for desorption and ionization of low molecular weight molecules like carbohydrates and amino acids. The newly synthesized material delivered excellent results in respect to signal-to-noise (S/N) ratio (S/N ratio: >9/1) and sensitivity (limit of detection (LOD): lower to ng/microL). Hyphenation of TLC to MELDI-MS employing the novel developed material simultaneously as chromatographic and mass spectrometric sorbent was shown for the first time for the analysis of low molecular weight molecules like mono- and oligosaccharides.

Quality assessment and quantitative analysis of flavonoids from tea samples of different origins by HPLC-DAD-ESI-MS.

Components of green tea ( Camellia sinensis) have been of considerable interest in recent years because of their potential utility as pharmaceutical agents, particularly for their antioxidant and anticarcinogenic activity. Responding to the increasing scientific validation of numerous health benefits of tea, a comprehensive approach was adopted to carry out analysis for the quality assessment of flavonoids in tea samples of different origins. For this purpose, extraction, separation, and mass spectrometric parameters were optimized. Extraction methods evaluated include reflux extraction, a modified accelerated solvent extraction (ASE), namely, Aquasolv extraction, and microwave-assisted extraction (MAE) using different percentages of solvents. Separation was performed by a specifically developed reversed phase high-performance liquid chromatography (RP-HPLC) method using different C18 and C8 stationary phases. Optimization of extraction techniques clearly proved the performance of MAE, which delivered highest yields in a very short time. Additionally, the comparison with Aquasolv extraction provided new insights, as variations in quantified amounts of target compounds between the extracts could be explained on the basis of thermal degradation and epimerization phenomena. Especially the epimerization phenomenon for catechin/epicatechin oligomers, that is, of procyanidins P 2 and P 3, was observed for the first time. Finally, an optimized extraction and separation system was used for qualitative and quantitative investigations of compounds from different green tea samples from Ceylon (cultivated under biologically controlled conditions), Japan, India, and China as well as from one black tea sample from India.